This disclosure relates to a method of forming a relief pattern by e-beam lithography using chemical amplification, and derived articles.
E-beam lithography using chemically amplified resists plays an important role in the fabrication of masks. There has been increasing interest in optimizing the properties of these chemically amplified resists for mask applications. In addition to the stability of the resist formulation, speed, sensitivity, resolution and line-edge roughness (LER) are also critical parameters. The resists are usually spun on the top of a 15 nanometer chromium (Cr) layer and need to have good etch properties to better transfer the pattern onto the metal layer. The etch rate, and isotropy (or anisotropy) determine the required film thickness. Higher etch rates require a thicker film, while a lower rate can work with a thinner resist film. Additionally, resists that operate over a range of post exposure bake temperatures are desirable. It is generally important that the bake temperatures are not too high and that the critical dimension (CD) varies minimally with small temperature fluctuations.
In view of the state of the prior art, it is desirable to develop new e-beam resists with high resolution, high sensitivity, and good profile control for generating patterns for use in mask fabrication. In particular, silicon-containing resists are desirable since increased silicon content improves the etch contrast between the patterned layer and the underlying substrate.